- Vologases III was the Emperor of Parthia between 110-147 CE.
- His reign is marked by the 20 year secession of western Parthia under Osroes I.
Western Parthia
- Between 109-129 CE, he lost western Parthia, which included Seleucia and Ctesiphon, to his rival Osroes I.
- In 116 CE, the Roman Emperor Trajan invaded Western Parthia during Trajan's Parthian War and captured both cities, displacing Osroes I from his throne in Ctesiphon, and replacing him with his son Parthamaspates. He also captured his daughter who remained a Roman Hostage until 129 CE.
- In 117 CE When Trajan died in 117 CE, Osroes I was reinstated as Ruler in Ctesiphon.
- In 129 CE, Vologases III finally removed Osroes I and reunited Parthia.
Ctesiphon